That will put the asteroid inside the orbit of communication satellites.

When the asteroid was discovered in 2004 scientists calculated a one-in-45 chance of an impact in 2029. Improved predictions later lifted the threat.

The asteroid's latest near approach will occur at midnight UK time tonight.

Members of the public can view the event online via the Slooh web-based sky-watching service, which collects images from observatories around the world.

Slooh President Patrick Paolucci said: "Alone among all these near-Earth asteroids that have passed our way in recent years, Apophis has generated the most concern worldwide because of its extremely close approach in 2029 and potential impact, albeit small, in 2036. We are excited to cover this asteroid live for the general public."

Scientists at the American space agency Nasa have calculated that if Apophis struck the Earth it would generate a blast equivalent to more than 500 megatons of TNT. In comparison, the most powerful hydrogen bomb ever detonated, the Soviet Tsar Bomba, released 57 megatons.